Radio communication system for vehicle

ABSTRACT

A radio communication system for a vehicle which allows communication not only between a driver and a passenger of one vehicle but also with a driver or a passenger of another vehicle without increasing the scale of a radio communication apparatus to be mounted on a helmet. A radio wave signaled from a radio wave transmitter-receiver of a driver or a passenger of a vehicle is received by a repeating apparatus of the self-vehicle and amplified by and re-signaled from the repeating apparatus. The radio wave signaled from the repeating apparatus is received by a radio wave transmitter-receiver of a driver or a passenger of another vehicle and reproduced by a speaker. A radio wave signaled from the radio wave transmitter-receiver of the driver or a passenger of the vehicle is received by a repeating apparatus of the self-vehicle and amplified by and re-signaled from the repeating apparatus. The radio wave signaled from the repeating apparatus is received by the radio wave transmitter-receiver of a driver or a passenger of the vehicle and reproduced by a speaker.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Divisional of U.S. application Ser. No.09/655,846 filed on Sep. 6, 2000, and claims priority under 35 U.S.C.§119 to Japanese Patent Application No. Hei-11-252349, filed Sep. 6,1999, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a radio communication system for a vehicle,and more particularly to a radio communication system for a vehiclewherein a radio communication apparatus is provided on a helmet andperforms radio communication with another radio communication apparatusprovided on another helmet through a repeating apparatus carried on avehicle.

2. Description of Background Art

A radio communication system to allow conversation between passengers ona two-wheeled vehicle includes a speaker, a microphone and atransmitter-receiver provided on a helmet for each of the passengers andthe radio communication apparatus communicates directly with each other.Such a radio communication apparatus is disclosed, for example, inJapanese Utility-Model Laid-open No. Sho 62-155535.

In order to make it possible to perform communication by a radiocommunication apparatus provided on helmets not only between a driverand a fellow passenger as described above but also with a passenger ofanother vehicle, a high output power signal is required. Accordingly, itis necessary to increase the scale of a drive circuit and a battery andadd a power saving circuit for reducing the power consumption or thelike. In addition, a problem occurs in that the apparatus becomes largein scale.

SUMMARY AND OBJECTS OF THE INVENTION

It is an object of the present invention to solve the problem of theprior art described above and provide a radio communication system for avehicle which allows communication not only between fellow passengersbut also with a passenger in another vehicle with low power consumptionwithout increasing the scale of a transmitter-receiver to be mounted ona helmet.

In order to attain the object described above, the present inventionincludes a radio communication apparatus mounted on each of helmets tobe worn by a driver and a passenger of the vehicle and includes at leasta speaker, a microphone and a radio wave transmitter-receiver. Arepeating apparatus is mounted on the vehicle side for communicatingwith the radio wave transmitter-receiver. The radio communicationapparatus mounted on the helmets communicate with each other through therepeating apparatus.

With the characteristic described above, since the radio communicationapparatus mounted on each helmet always transmits to the repeatingapparatus irrespective of the position of the radio communicationapparatus of the other party, it is required only to provide thetransmitter-receiver of the radio communication apparatus with a minimumtransmission capacity required for communication over a very shortdistance with the repeating apparatus. Thus, a reduction in the size andthe weight of the transmitter-receiver and a reduction in the powerconsumption occurs.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a view schematically illustrating a communication methodbetween fellow passengers by a radio communication system for a vehicleto which the present invention is applied;

FIG. 2 is a view schematically illustrating a communication methodbetween additional individuals other than the fellow passengers by aradio communication system for a vehicle to which the present inventionis applied;

FIG. 3 is a perspective view illustrated partially in a broken away viewan embodiment of a transmitter-receiver;

FIG. 4 is a front elevational view showing partially in a broken awayview an internal construction of the transmitter-receiver;

FIG. 5 is a block diagram of the radio communication system for avehicle of the embodiment of the present invention;

FIG. 6 is a view illustrating operation of a mix/mute section in theform of a table;

FIG. 7 is a perspective view of an instrument panel and associatedmembers of a vehicle according to the embodiment of the presentinvention;

FIG. 8 is a side elevational view of a motorcycle to which the radiocommunication system for a vehicle of the present invention is applied;

FIG. 9 is a perspective view of a front portion of the vehicle;

FIG. 10 is a system construction diagram of a navigation system;

FIG. 11 is a perspective view of the front showing the instrument paneland associated members of the vehicle;

FIG. 12 is a perspective view of an essential part showing theinstrument panel and associated members of the vehicle;

FIG. 13 is a perspective view of a PDA accommodation box illustrating astate in which a cover is open;

FIG. 14 is a state transition diagram in the navigation system;

FIG. 15 is a view showing a display example (1) of the PDA displayingpanel;

FIG. 16 is a view showing a display example (2) of the PDA displayingpanel;

FIG. 17 is a view showing a display example (3) of the PDA displayingpanel;

FIG. 18 is a view showing a display example (4) of the PDA displayingpanel;

FIG. 19 is a view showing a display example (5) of the PDA displayingpanel;

FIG. 20 is a view showing a display example (6) of the PDA displayingpanel;

FIG. 21 is a side elevational view of a front portion showing the boxprovided above the instrument panel;

FIG. 22 is an enlarged sectional view of essential part of FIG. 21;

FIG. 23 is a sectional view of essential part of the vehicle when thebox is accommodated; and

FIG. 24 is an exploded perspective view according to a modification tothe box which accommodates a PDA.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, the present invention is described in detail withreference to the drawings. FIGS. 1 and 2 are views schematicallyillustrating communication methods by a radio communication system for avehicle to which the present invention is applied, and here, it isdescribed taking communication between four passengers on two vehiclesas an example.

On a helmet 70 worn by each passenger, a radio communication apparatus 1including a microphone 71, a speaker 72 and a radio wavetransmitter-receiver 73 is provided. The radio wave transmitter-receiver73 has a whip antenna with a contracted coil, which is hereinafterdescribed, built therein, and the antenna is not exposed outside theradio wave transmitter-receiver 73. The radio wave transmitter-receiver73 is removably mounted at the center of a rear portion of the helmet 70through a removable fixing member.

A repeating apparatus 74 for radio communication with the radio wavetransmitter-receivers 73 is provided on each vehicle. The repeatingapparatus 74 includes a down-converter not shown that converts an outputvoltage (for example, 12 V) of a vehicle-carried battery 75 into apredetermined driving voltage (for example, 5 V) and uses thepredetermined driving voltage as a driving source.

In such a construction as described above, in order for passengers ofthe same vehicle, that is, a driver and a fellow passenger, tocommunicate with each other, as illustrated in FIG. 1, for example, thevoice of the driver is detected and converted into a sound signal by themicrophone 71 and transferred to the radio wave transmitter-receiver 73.The radio wave transmitter-receiver 73 of the driver communicates withthe radio wave transmitter-receiver 73 of the fellow passenger throughthe repeating apparatus 74 of the same vehicle.

On the other hand, in order for passengers operating different vehiclesto communicate with each other, as illustrated in FIG. 2, a radio wavesignaled from the radio wave transmitter-receiver 73A of the driver ofthe vehicle 1A is received by the repeating apparatus 74A of the samevehicle and amplified by and re-signaled from the repeating apparatus74A. The radio wave signaled from the repeating apparatus

A is received by the radio wave transmitter-receiver 73A of the fellowpassenger while it is received simultaneously by the radio wavetransmitter-receivers 73B of the driver and the fellow passenger of thevehicle 1B and reproduced by the speaker 72B.

On the other hand, a radio wave signaled form the radio wavetransmitter-receiver 73B of the driver of the vehicle 1B is received bythe repeating apparatus 74B of the same vehicle and amplified by andre-signaled from the repeating apparatus 74B. The radio wave signaledfrom the repeating apparatus 74B is received by the radio wavetransmitter-receiver 73B of the fellow passenger while it is receivedsimultaneously by the radio wave transmitter-receivers 73A of the driverand the fellow passenger of the vehicle 1A and reproduced by the speaker72A.

FIG. 3 is a perspective view partially in a broken away view of theradio wave transmitter-receiver 73, and FIG. 4 is a front elevationalview taken partially in a broken away view showing an internal structureof the radio wave transmitter-receiver 73.

The radio wave transmitter-receiver 73 includes a circuit board 806, acell 803 of the size of a AAA battery and a whip antenna 802 with acontracted coil built in a parallelepiped resin case 804, and thecircuit board 806 and the cell 803 that is the size of a AAA batteryhave comparatively a large mass and are disposed such that they aredistributed to the left and the right in the resin case 804 to provide aweight balance when the radio wave transmitter-receiver 73 is mounted atthe center of a rear portion of the helmet 70. The whip antenna 802 witha contracted coil is accommodated such that it crawls along an innerside in the resin case 804.

A seesaw switch 807 for providing a sound volume adjustment and a powersupply switch 808 are mounted together with various circuit elements onthe circuit board 806. Operation buttons 801 and 805 for the switches807 and 808 are exposed to the left side of a face which is positionedon a rear face where the radio wave transmitter-receiver 73 is mountedat the center of the rear portion of the helmet 70.

Since, in the present embodiment, the circuit board 806 and the cell 803of the size of a AAA battery which have comparatively great masses aredisposed such that they are distributed to the left and the right in theresin case 804, even if the transmitter-receiver 73 is mounted at thecenter of the rear portion of the helmet 70, the weight balance of theentire helmet is maintained. In such a situation the mounting feeling ofthe helmet is not deteriorated nor does the handling of the helmetbecome difficult.

Further, when the radio wave transmitter-receiver 73 is mounted on therear central portion of the helmet 70, since the operation buttons 801and 805 for the switches are provided on the back face, opposite to thehelmet, of the radio wave transmitter-receiver 73, they can be readilyoperated and accurately operated with either the left or the right hand.Furthermore, since the operation buttons 801 and 805 are provided on theleft side on the rear face, an operation of the buttons particularlywith the left hand is easy, and also during driving, it can be operatedwithout taking the hand from the throttle grip.

FIG. 5 is a block diagram of an embodiment of the radio communicationsystem for a vehicle described above, and like reference numerals tothose described above represent like elements.

The radio wave transmitter-receiver 73 of the radio communicationapparatus 701 is mounted on each helmet and includes an amplifier 731for amplifying a sound signal detected by the microphone 71, andtransmits the amplified sound signal from a transmission channel T1. Theradio wave transmitter-receiver 73 further includes an amplifier 732 foramplifying a sound signal received by a reception channel R1 and outputsthe amplified sound signal from the speaker 72. The amplification factorof the amplifier 732 is controlled by a sound volume control section733.

In the repeating apparatus 74, a transmission-reception section 741 hasa first reception channel R1, a second reception channel R2, a firsttransmission channel T1 and a second transmission channel T2. The firstand second reception channels R1 and R2 receive sound signalstransmitted from the different radio wave transmitter-receivers 73. Thefirst transmission channel T1 transmits sound signals to the differentradio wave transmitter-receivers 73. The second transmission channel T2transmits control signals to the different radio wavetransmitter-receivers 73.

A mixing section 742 combines and outputs sound signals received by thefirst and second reception channels R1 and R2 of thetransmission-reception section 741. A mix/mute section 743 mixes soundsignals outputted from the mixing section 742, a portable telephone set81, another radio set 82, a music reproduction apparatus 83 such as aradio set, an MD or CD apparatus, a sound board 84 and so forth andprovides a resulting signal to the first transmission channel T1 of thetransmission-reception section 741. It is to be noted that, where thevehicle carries a navigation system 86 as in the present embodiment,also a sound signal signaled from the navigation system 86 is mixed. Thesound board 84 converts the present time, a gear position, a state of adirection indicator or the like into a sound signal and outputs thesound signal.

The mix/mute section 743 has a mute function and attenuates orinterrupts (mutes), when a sound source (for example, the portabletelephone set 81) having a higher priority order and another soundsource (for example, the music reproduction apparatus 83) having a lowerpriority order interferes with each other. The signal signaled from thesound source having a lower priority order is hereinafter described indetail.

A controller 744 produces a control signal in response to an operationof a switch provided on an operation panel 85 which is hereinafterdescribed, and provides the control signal to the mix/mute section 743or the second transmission channel T2 of the transmission-receptionsection 741. On the operation panel 85, a sound volume adjustment switch851, a mute switch 852, a PTT switch 853 and a telephone/radiochangeover switch 854 are provided.

FIG. 6 is a view showing the action of the mix/mute section 743 in theform of a table. If the sound volume adjustment switch 851 is operated,then the controller 744 produces a sound volume increasing/decreasingsignal in response to the operation of the sound volume adjustmentswitch 851 and signals the sound volume increasing/decreasing signal tothe transmission-reception section 741. The transmission-receptionsection 741 transmits the sound volume increasing/decreasing signal fromthe second transmission channel T2. The sound volumeincreasing/decreasing signal is received by the second receptionchannels R2 of the radio wave transmitter-receivers 73 of the radiocommunication apparatus 701 and inputted to the individual sound volumecontrol sections 733. Each sound volume control section 733 controls theamplification factor of the amplifier 732 in response to the receivedsound volume increasing/decreasing signal.

If the mute switch 852 is operated, then the controller 744 produces amute signal in response to the operation of the mute switch 852 andsignals the mute signal to the mix/mute section 743. The mix/mutesection 743 attenuates (or interrupts) output signals of the musicreproduction apparatus 83, sound board 84 and mixing section 742 whileit outputs output signals of the telephone set 81 and the radio set 82as they are.

If the PTT switch 853 is switched on while the telephone/radiochangeover switch 854 is switched to the telephone side, then the outputsignals of the radio set 82, music reproduction apparatus 83 and soundboard 84 are attenuated by the mix/mute section 743. If the PTT switchis depressed while the telephone/radio changeover switch is switched tothe radio side, then the output signals of the portable telephone set81, music reproduction apparatus 83 and sound board 84 are attenuatedsimilarly.

FIG. 8 is a side elevational view of a motorcycle on which the repeatingapparatus 74 of the radio communication system for a vehicle describedabove is carried, and FIG. 9 is a perspective view of an essential partof the motorcycle. The motorcycle (hereinafter referred to as “vehicle”)1 of the scooter type has a body frame 2 of the double cradle type whichextends in the forward and backward direction of a vehicle body. A headpipe 3 is mounted at a front end of the body frame 2, and a front wheel5 is mounted at an end of a front fork 4 which extends downwardly fromthe head pipe 3. An upper portion of the front wheel 5 is covered with afront fender 6. A handlebar 7 is secured to an upper portion of thefront fork 4, and front and rear portions of the handlebar 7 are coveredwith a handle cover 33 which is divided into two forward and backwardportions.

A transparent window screen 34 is provided on the handle cover 33 by astay not shown, and a screen garnish 35 as a cover member is provided ata lower portion of a front face of the window screen 34. The repeatingapparatus 74 is disposed at the rear portion of an instrument panelinside of the screen garnish 35. A PDA accommodation box (hereinafterreferred to merely as “box”) 100 which can accommodate therein a PDA(details of which are hereinafter described) used for the navigationsystem is provided on the handle cover 33. The box 100 is supported forrocking motion in directions indicated by an arrow mark NA.

A fuel tank 8, a radiator reservoir tank 9, and a radiator 10 areprovided in a cradle space surrounded by pipes of the body frame 2, anda power unit 12 having a water-cooled engine 11 provided at a frontportion thereof is provided rearwardly of the cradle space. The powerunit 12 is mounted for rocking motion on the body frame 2 with a frontportion thereof suspended by a link mechanism 13 and with a rear endportion thereof suspended by a rear cushion 14. A rear wheel 15 ismounted at a rear portion of the power unit 12, and the body frame 2 iscovered with a body cover 17 and a seat 16 is disposed at a rear upperportion of the body frame 2.

A front portion of the body cover 17 is formed from a front cover 21which covers a front portion of the head pipe 3 and an upper portion ofthe front wheel 5 and an inner cover 22 which covers a rear portion ofthe front cover 21. A pair of left and right floor steps 23 on which thefeet of a driver are placed extend rearwardly from the inner cover 22,and a pair of floor skirts 24 extend downwardly from outer edges of thefloor steps 23. An under cover 25 provides a cover between the lowerends of the floor skirts 24, and a center cover 26 which extendsrearwardly from the inner cover 22 which covers a longitudinally centralportion of the body frame 2. The opposite side faces of a rear portionof the body frame 2 are covered with side covers 27 extending rearwardlyfrom the center cover 26.

A pair of left and right lower side covers 28 extend downwardly fromouter edges of the side covers 27, and a lower portion of the rear endof the body frame 2 is covered with a rear center cover 29 providedrearwardly of the lower side covers 28. An upper portion of the rear endof the body frame 2 is covered with a rear upper cover 30 provided abovethe rear center cover 29.

A headlamp 41 and direction indicator lights 42 are mounted on the frontcover 21. Further, a GPS sensor 110 which receives GPS satellite radiowaves for a navigation system and outputs measurement position data andan MPU 111 serving as a system controller for controlling the navigationsystem are disposed on the front cover 21. It is to be noted that thelocation of the GPS sensor 110 is not limited to the front portion ofthe vehicle body, but it may be mounted at such a position of a rear endportion of the vehicle body (reference character 110 a) which is nothidden by a driver such as, for example, the rear upper cover 30. A pairof air inlet ports 35 a, 35 a are provided in the screen garnish 35, andair flowing along the front face of the front cover 21 flows upwardlyand is introduced into the air inlet ports 35 a.

A fuel supply lid 43 and an ignition plug-checking lid 44 are providedat part of the center cover 26. A main stand 45 is provided at a lowerportion of the vehicle body, and an air cleaner 46 is provided in theinside of the lower side covers 28. Further, a rear grip 47, a tail lamp48, and a rear fender 49 are provided at rear portions of the vehiclebody.

FIG. 10 is a system block diagram of the navigation system. To the MPU111 as a system controller for managing navigational operations in aconcentrated manner, the GPS sensor 110 and a PDA 200 which isaccommodated in the box 100 are connected. It is to be noted that a PDAis known as an information apparatus for personal use having a functionof managing a schedule of a person and so forth, a display panelfunction for allowing inputting with a pen, a function of searching alarge amount of information such as a dictionary, a manual and so forthbuilt therein, and so forth, and the present embodiment makes itpossible to use those functions as navigational functions by storage andsearch of map information. Also a switch 102 for causing switching orscrolling of a display screen of the PDA 200 to be performed forcontracting or expanding a map is provided on the box 100, and also theswitch 102 is connected to the MPU 111. Power supply to the MPU 111 isderived from a battery 112 carried on the vehicle. While the PDA 200 hasa battery in the inside thereof, when it is connected to and usedtogether with the MPU 111, it can receive a supply of power from thebattery 112 through the MPU 111.

The PDA 200 has a memory into which travel data can be stored and adisplay screen, and provides navigation information in accordance withmeasurement position data from the GPS sensor 110 and a control signalfrom the MPU 111 to perform navigational operations. The travel dataincludes electronic map information and route information to adestination. The travel data is produced, for example, based oninformation obtained from a network such as the Internet using apersonal computer and electronic map information. A travel route isproduced by providing a destination as input information, and a waypoint such as a main intersection on the route is selected in accordancewith an algorithm set in advance if the route is determined. The traveldata may be inputted from a personal computer or information stored inadvance in a ROM or the like may be transferred as the travel data.

The MPU 111 supplies a control signal c1 to the GPS sensor 110, and theGPS sensor 110 receives GPS satellite radio waves in accordance with thecontrol signal c1. The GPS sensor 110 inputs measurement position datad1 based on the GPS satellite radio waves to the MPU 111. The MPU 111analyzes the measurement position data d1 and an instruction signal d2from the switch 102 and supplies a control signal c2 and measurementposition data d1 to the PDA 200. The PDA 200 is started up by thecontrol signal c2, executes a predetermined program using themeasurement position data d1 and displays navigational information onthe display panel. The PDA 200 inputs a status signal d3 indicative ofan operational status to the MPU 111.

Subsequently, a mounted manner of the box 100 in which the PDA 200described above is accommodated is described. FIG. 7 is a sidewardperspective view of a front portion of the vehicle on which the box 100is mounted, FIG. 11 is a front perspective view of the vehicle, and FIG.12 is a front perspective view showing a manner wherein the PDA 200 ismoved (pivoted) to a position for non-use. In FIGS. 7, 11 and 12, likereference numerals to those of FIG. 8 denote like elements. It is to benoted that, in FIGS. 7, 11 and 12, a state wherein the window screen 34is removed is illustrated. An instrument panel (meter) 50 isincorporated in the handle cover 33. A speedometer 51 is provided at thecenter of the face of the instrument panel 50, and a fuel gauge 52 isprovided on the left side of the instrument panel 50 while a watertemperature gauge 53 is provided on the right side of the instrumentpanel 50.

A hazard switch 54 is provided in an upper stage of the front faceadjacent on the right side of the instrument panel 50 while a starterswitch 55 is provided in a lower stage, and a kill switch 56 is providedon an upper face. Further, a direction indicator switch 57 is providedin an upper stage of the front face adjacent on the left side of theinstrument panel 50 while a horn switch 58 is provided in a lower stage,and the operational panel 85 and a high beam/low beam switch 59 areprovided on an upper face.

The box 100 is mounted along a lower edge of the instrument panel 50.The box 100 is so dimensioned and shaped that a PDA having a memory inwhich map information to be used for the navigation system can be storedand a display panel can be accommodated in the box 100. A window 101 inwhich a transparent glass plate, a transparent acrylic sheet or the likeis provided so that the display panel of the PDA 200 accommodated in thebox 100 may be observed therethrough and a switch 102 are provided onthe box 100. For the switch 102, a switch which can be operatedleftwardly, rightwardly, upwardly and downwardly as indicated by arrowmarks in FIG. 11 is used, and a click to the left or the right is usedfor the switching of the display panel of the PDA 200 whereas a click toupwards or downwards is used for an enlargement or contraction of a mapor the like. A face 103 of the box 100 on which the window 101 and theswitch 102 are provided is formed as a lid, and removal or insertion ofa PDA is performed with the lid 103 opened. A knob 104 is provided onthe lid 103 such that the lid 103 can be latched and unlatched byturning the knob 104. Preferably, the knob 104 can be operated to latchand unlatch by means of an engine key for the sake of security.

The box 100 has a pair of pivot shafts 105 projecting leftwardly andrightwardly, and each of the pivot shafts 105 is supported by a bearing(not shown) incorporated in the handle cover 33. When the navigationsystem is to be used, the box 100 is lifted up (popped up) by springmeans not shown to a position (first position) in which the display faceof the PDA is substantially in register with the face of the instrumentpanel 50 as shown in FIGS. 7, 8 and 11. On the other hand, when thenavigation system is not used, the box 100 can be pushed down so as tobe retracted to a position (second position) in which the display faceof the PDA, that is, the window 101, lies substantially in a verticalplane. Preferably, arresting means such as a magnetic catch is providedon the rear face of the box 100 and the handle cover 33 so that the box100 may be fixed to the handle cover 33 in the retracted position.

Preferably, each of the pivot shafts 105 has a rotational damperprovided therefor which acts against the spring means described abovewhen the box 100 is pivoted from the retracted position (position ofFIG. 12) to the use position (position of FIG. 7). This is because it isconvenient for smooth pivotal motion of the box 100 and for protectionof the PDA from vibrations of the vehicle and prevention of vibrationsof the display screen. An oil damper wherein oil is enclosed in apackage can be used for the rotational dampers. This damping actionfunctions only when the box is pivoted to the first position, but thedamper action does not function upon pivotal motion from the firstposition to the second position. Accordingly, when the GPS displayscreen, that is, the display panel of the PDA, is to be observed, thescreen can be pivoted moderately from the retracted position (secondposition), but when the screen is to be retracted, it can be retractedrapidly.

FIG. 13 is a perspective view of the box 100 illustrating a statewherein the lid 103 is open. A repeating section 107 having a connector106 of multiple poles for coupling to input/output terminals of the PDA200 is provided in the box 100. The repeating section 107 repeats asignal from the connector 106 to the MPU 111, and repeats a signal ofthe switch 102 to the MPU 111 over a cable 108. The PDA 200 can beremovably mounted into the box 100 through the connector 106.

Accordingly, when a person gets on the vehicle, the PDA 200 can beconnected to the connector 106 and incorporated as a navigation system.Further, when the driver intends to leave the vehicle, he/she candisconnect the PDA 200 from the connector 106 and draw out the PDA 100from the box 100 and then carry it independently of the navigationsystem. Since the PDA 200 is accommodated in the box 100 in this manner,the PDA 200 can be removed readily from the vehicle. Consequently, thisis convenient from the point of view of the prevention of burglary andthis is also convenient where the PDA 200 is used as a multi-functioninformation apparatus such that it is used as an address book or adictionary without using it for navigation. Further, since also aconnection section to a PDA is accommodated in the box 100, also theinfluences of rain, wind, dust and so forth can be suppressed to be low.

A status transition of the navigation system is described with referenceto a status transition diagram of FIG. 14 and examples of the displayscreen (FIGS. 15 to 20). Referring to FIG. 14, in status SO, thenavigation system is waiting for reception of data. When data is in thememory of the PDA 200 or when reception of data comes to an endregularly, the status advances to status S1. In status S1, thenavigation system further waits for reception of data and waits astarting instruction. In statuses S0 and S1, a title screen P1 of FIG.15 is displayed on the display panel.

If the switch 102 is clicked to the left in status S1, then the statusadvances to status S2. In status S2, an arrow mark navigation displayscreen is displayed (refer to FIG. 16). On the arrow mark navigationdisplay screen, an arrow mark N1 indicative of a direction to a waypoint and a dot mark N2, a name N3 of the way point, a numeral N4indicative of a great circle distance to the way point and a graphicimage N5 which indicates a decrease of the distance N4 to the way pointin the form of a bar graph are displayed.

If the switch 102 is clicked to the left in status S2, then the statusadvances to status S3. In status S3, a frame map navigation screen isdisplayed (refer to FIG. 17). On the frame map navigation screen, anarrow mark N6 of a shape of a way point and an advancing direction isdisplayed in a large size, and the direction to the way point isindicated by a small arrow mark N7. If the switch 102 is clicked to theleft in status S3, then the status advances to status S4, but if theswitch 102 is clicked to the right, then the status returns to statusS2. In status S4, a map navigation screen is displayed. In this statusS4, the map is fixed.

If the switch 102 is clicked to the left in status S4, then the statusadvances to status S5, but if the switch 102 is clicked to the right,then the status returns to status S3. In status S5, a map navigationscreen with a travel locus is displayed in addition to the display instatus S4 (refer to FIG. 18). An arrow mark N8 in FIG. 18 indicates theposition of the self-vehicle and the travelling direction, and the locusis indicated by a dot N9.

If the switch 102 is clicked to the left in status S5, then the statusadvances to status S6, but if the switch 102 is clicked to the right,then the status returns to status S4. In status S6, a map navigationscreen on which only the travelling locus is shown except a map isdisplayed.

If the switch 102 is clicked to the left in status S6, then the statusadvances to status S7, but if the switch 102 is clicked to the right,then the status returns to status S5. In status S7, a map navigationscreen is displayed in a state wherein the position of the self-vehicleis fixed. Accordingly, a screen on which the map is scrolled as theself-vehicle travels is displayed.

If the switch 102 is clicked to the left in status S7, then the statusadvances to status S8, but if the switch 102 is clicked to the right,then the status returns to status S6. In status S8, a map navigationscreen with a travel locus shown in a state wherein the position of theself-vehicle is fixed is displayed.

If the switch 102 is clicked to the left in status S8, then the statusadvances to status S9, but if the switch 102 is clicked to the right,then the status returns to status S7. In status S9, a map navigationscreen only with a travel locus shown except a map in a state whereinthe position of the self-vehicle is fixed is displayed.

If the switch 102 is clicked to the left in status S9, then the statusadvances to status S10, but if the switch 102 is clicked to the right,then the status returns to status S8. In status S10, the arrangement ofsatellites is displayed (refer to FIG. 19). In FIG. 19, satellites N10being used, satellites N11 in a standby state and satellites N12 undersearch are displayed together with the direction.

If the switch 102 is clicked to the left in status S10, then the statusadvances to status S11, but if the switch 102 is clicked to the right,then the status returns to status S9. In status S11, latitude andlongitude indicative of the position of the self-vehicle are displayed(refer to FIG. 20). On this display screen, a travelling speed,latitude, longitude and advancing direction are indicated on the displayscreen.

If the switch 102 is clicked to the left in status S11, then the statusreturns to status S2, and if the switch 102 is clicked to the right instatus S2, then the status skips statuses S3 to S10 and advances tostatus S11.

While the status transition diagram described above illustrates anexample of transition which proceeds in response to an operation of theswitch 102, it is possible to perform switching between the arrow marknavigation display and the frame map navigation display in response tothe position of the self-vehicle to a way point. For example, the arrowmark navigation display is displayed up to a point 400 m short of a waypoint, and then when the point 400 m short of the way point is reached,the display is switched from the arrow mark navigation display to framemap navigation display. Further, when the self-vehicle is spaced by 50 mfrom the way point after it passes the way point, or when theself-vehicle does not advance straightforwardly across an intersectionand is directed to an intersection leaving direction, the way point ofthe object is switched and switching from the frame map navigationdisplay to the arrow mark navigation display is performed. Further, theway point is automatically updated when the self-vehicle goes out of thepreset travel route.

Subsequently, modifications are described. While, in the embodimentdescribed above, the box 100 in which a PDA 200 is accommodated ismounted along the lower edge of the instrument panel 50, the position atwhich the box 100 is to be mounted is not limited to this position, andit can be mounted above the instrument panel 50. FIG. 21 is a sideelevational view of a front portion of a vehicle showing the box 100provided above the instrument panel 50, and FIG. 22 is an enlargedsectional view of an essential part of FIG. 21. Further, FIG. 23 is asectional view when the box 100 is accommodated in a stored position.

An upper plate 60 forms part of a cover 61 which covers an upper portionof the instrument panel 50, and is supported for pivotal motion on thecover 61 by a hinge 62. To an end portion of the upper plate 60, thatis, to an end portion of the upper plate 60 opposite to the sidesupported by the hinge 62, an upper edge of the box 100 foraccommodating a PDA 200 therein is connected by a hinge 63. Further,opposite ends of a lower end of the box 100 are provided with a pair ofsliders 65 which fit with and slidably move on a pair of two (only oneis shown) rails 64 provided separately on the left and right of thevehicle body.

By the construction described above, if the upper plate 60 is liftedfrom a state wherein the box 100 is folded as shown in FIG. 23, thensince the box 100 is coupled to an end portion of the upper plate 60 bythe hinge 63, it is lifted by the upper plate 60. Meanwhile, the loweredge of the box 100 slidably moves on the rails 64 by means of thesliders 65 and is guided to an end portion of the rails 64 (a ratherrear portion of the vehicle body). Consequently, as shown in FIGS. 21and 22, the box 100 is lifted with the display panel face of the PDA 200directed toward the driver until the display face of the instrumentpanel 50 and the display panel face of the PDA become substantiallyparallel to each other, thereby entering a state wherein the individualdisplays can be observed readily. Further, if a portion of the box 100in the proximity of the lower edge is pushed with a finger to depressthe upper plate 60 from the state of FIGS. 21 and 22, then the box 100is accommodated into the cover 61 in a state wherein the display panelface of the PDA 200 is directed downwardly as shown in FIG. 23.

While, in the embodiment described above, the lid 103 supported by ahinge is opened and the PDA 200 is inserted or removed, the structure ofthe box 100 is not limited to this. FIG. 24 is a perspective view of amodification to the box 100. An opening 66 through which a PDA 200 is tobe removed or inserted is provided at an end surface of a box 100A, anda lid 67 fits in the opening 66. On the box 100A, a window 101 throughwhich the display panel of a PDA accommodated in the box 100A can beobserved and a switch 102 as well as a connector for connection of theterminals of a PDA 200 and so forth (not shown) are provided similarlyas in the embodiment of FIG. 13.

Where a PDA 200 is incorporated in and used together with a navigationsystem, the lid 67 is opened and the PDA 200 is inserted into the box100A through the opening 66, and then the lid 67 is fitted into theopening 66 to close up the box 100A. On the other hand, when the PDA 200incorporated in the navigation system is not used, the lid 67 is removedto open the opening 66, and the PDA 200 is removed from the box 100A.

It is to be noted that preferably a packing or a seal to provide for awaterproof or dust proof container is interposed between a fitting faceof the box 100 and the lid 103 therefor or between the fitting face ofthe box 100A and the lid 67 therefor, described hereinabove withreference to FIGS. 13 and 24 and so forth.

According to the present invention, the following effects are achieved.

(1) Since the radio communication apparatus provided on the helmets forindividual passengers communicate with each other through a repeatingapparatus carried on a vehicle, it is required only to provide each ofthe radio communication apparatus with a minimum transmission capacityrequired for communication over a very short distance with the repeatingapparatus. Thus, a reduction in the size and the weight of the radiocommunication apparatus and a reduction of the power consumption areallowed.

(2) Since a transmitter-receiver of each of the radio communicationapparatus is mounted at the center of a rear portion of a helmet, thesituation where the mounting feeling of the helmet is deteriorated orhandling of the helmet becomes difficult does not occur.

(3) Since the repeating apparatus carried on the vehicle side mixes asound signal outputted from a navigation system, a portable telephoneset, a music reproduction apparatus for an MD or a CD or the like with areceived sound signal and transmits the mixed signal, the hearing ofsound information signaled from the navigation system or the like is notinterrupted by a conversation with another passenger.

Further, since sound of the navigation system can be heard not only by adriver and a fellow passenger but also by a passenger of another vehiclesimultaneously, upon touring by a plurality of vehicles, the drivers ofthe vehicles can commonly share information conveniently.

Furthermore, if it is made possible to hear the sound of the navigationsystem independently of a display of the navigation system, thennavigation only with sound is possible.

(4) Since, when a received sound signal and another sound signaloutputted from a music reproduction apparatus are mixed and transmitted,a predetermined one of the sound signals can be selectively attenuatedor interrupted (muted), a sound signal having a higher degree ofimportance (or priority) is not disturbed by another sound signal havinga lower degree of importance.

(5) Since a circuit board and a power supply (battery) which havecomparatively large masses are disposed in the transmitter-receiver tobe mounted on each helmet such that they are distributed on the left andthe right in a case, even if the transmitter-receiver is mounted at thecenter of a rear portion of the helmet, the weight balance of the entirehelmet is maintained,

(6) Since operation buttons of the transmitter-receiver to be mounted oneach helmet are provided on a comparatively wide face which ispositioned on a rear face where the transmitter-receiver is mounted atthe center of a rear portion of the helmet, the operation buttons can beformed with a larger size and can be operated readily and accuratelyeven if a glove is worn on a hand.

(7) Since an antenna of the transmitter-receiver is reduced in size andweight and the size of a circuit board is suppressed to a size equal tothat of a cell of the size of a AAA battery, by using a cell of the sizeof a AAA battery as a power supply, the dead space in thetransmitter-receiver is reduced and miniaturization is allowed.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. A radio communication system for a vehicle comprising: a radiocommunication apparatus mounted on helmets to be worn by a driver and apassenger of said vehicle and including at least a speaker, a microphoneand a radio wave transmitter-receiver; and a repeating apparatus mountedon said vehicle side for communicating with said radio wavetransmitter-receiver; said radio communication apparatus mounted on oneof said helmets communicating with a second of said helmets through saidrepeating apparatus.
 2. The radio communication system for a vehicleaccording to claim 1, wherein said repeating apparatus repeats mutualcommunication between two radio communication apparatus mounted on eachof the two helmets and a radio communication apparatus mounted on athird helmet worn by a person other than the passenger or the driver ofsaid vehicle.
 3. The radio communication system for a vehicle accordingto claim 1, wherein the repeating apparatus includes a mute function andattenuates or interrupts when a sound source having a higher priorityorder and another sound source having a lower priority order interferewith each other.
 4. The radio communication system for a vehicleaccording to claim 2, wherein said radio wave transmitter-receiver isremovably mounted at the center of a rear portion of each of the helmetsthrough a removable fixing member.
 5. The radio communication system fora vehicle according to claim 1, wherein said repeating apparatusincludes a mixing apparatus to which at least one sound signalgeneration apparatus which generates a sound signal is connected andwhich mixes a sound signal or signals outputted from said sound signalgenerating apparatus with the received sound signal and transmits aresulting signal.
 6. The radio communication system for a vehicleaccording to claim 2, wherein said repeating apparatus includes a mixingapparatus to which at least one sound signal generation apparatus whichgenerates a sound signal is connected and which mixes a sound signal orsignals outputted from said sound signal generating apparatus with thereceived sound signal and transmits a resulting signal.
 7. The radiocommunication system for a vehicle according to claim 3, wherein saidrepeating apparatus includes a mixing apparatus to which at least onesound signal generation apparatus which generates a sound signal isconnected and which mixes a sound signal or signals outputted from saidsound signal generating apparatus with the received sound signal andtransmits a resulting signal.
 8. The radio communication system for avehicle according to claim 4, wherein said repeating apparatus has amute function of selectively muting by attenuating or interrupting atleast one of the sound signals outputted from said sound signalgeneration apparatus.
 9. The radio communication system for a vehicleaccording to claim 4, wherein said sound signal generation apparatus isat least one of a navigation system, a portable telephone set, a musicreproduction apparatus, some other radio apparatus and a sound board.10. The radio communication system for a vehicle according to claim 5,wherein said sound signal generation apparatus is at least one of anavigation system, a portable telephone set, a music reproductionapparatus, some other radio apparatus and a sound board.
 11. The radiocommunication system for a vehicle according to claim 1, wherein saidradio wave transmitter-receiver has an antenna for radio communicationbuilt inside the case of the transceiver-receiver.
 12. The radiocommunication system for a vehicle according to claim 1, wherein saidradio wave transmitter-receiver has at least a circuit board and abattery accommodation section, and said circuit board and said batteryaccommodation section are disposed in such a manner as to be distributedto the left and the right when said radio wave transmitter-receiver ismounted in a predetermined posture at the center of the rear portion ofeach of the helmets.
 13. The radio communication system for a vehicleaccording to claim 12, wherein said battery accommodation section issized to correspond to the magnitude of a cell of a size of a AAAbattery, the size being equivalent to a size of said circuit board. 14.The radio communication system for a vehicle according to claim 1,wherein the operation buttons are a volume control switch and a powersupply switch.
 15. The radio communication system for a vehicleaccording to claim 6, wherein a display apparatus of a navigation systemis supported for movement between a use position and an accommodationposition.
 16. A radio communication system for a vehicle comprising: aradio communication apparatus mounted on each of helmets to be worn by adriver and a passenger of said vehicle and including at least a speaker,a microphone and a radio wave transmitter-receiver powered by a batteryhoused within a case of the transmitter-receiver, said radio wavetransmitter-receiver including: a pair of operation buttons disposed oneabove another on one side of a rear face of the case, the operationsbuttons being disposed on either a right side or a left side of thecase, and the battery being disposed in the right or the left side ofthe case opposite to the side where the operations buttons are disposed;and a repeating apparatus mounted on said vehicle side for wirelesscommunication with said radio wave transmitter-receiver, said radiocommunication apparatus being mounted on one of said helmetscommunicating with a second of said helmets through said repeatingapparatus, wherein said repeating apparatus repeats mutual communicationbetween two radio communication apparatus mounted on each of the twohelmets worn by the driver and the passenger of said vehicle and a radiocommunication apparatus mounted on a third helmet worn by a person otherthan the driver of the passenger of said vehicle, the repeatingapparatus including: a mixing section for combining signals receivedfrom two or more radio communication apparatuses; and a mix/mute sectionfor mixing sound signals outputted from the mixing section, a portabletelephone set, and a music reproduction apparatus, and providing anoutput transmission signal.
 17. The radio communication system for avehicle according to claim 16, wherein the mix/mute section includes amute function and attenuates or interrupts, when a sound source having ahigher priority order and another sound source having a lower priorityorder interferes with each other.
 18. The radio communication system fora vehicle according to claim 16, wherein the operation buttons are avolume control switch and a power supply switch.
 19. The radiocommunication system for a vehicle according to claim 1, wherein saidradio wave transmitter-receiver has a coil antenna accommodated along anupper inner side of the case of the radio transmitter-receiver.
 20. Theradio communication system for a vehicle according to claim 16, whereinsaid radio wave transmitter-receiver has a coil antenna accommodatedalong an upper inner side of the case of the radio transmitter-receiver.21. A radio communication system for a vehicle comprising: a radiocommunication apparatus mounted on each of helmets to be worn by adriver and a passenger of said vehicle and including at least a speaker,a microphone and a radio wave transmitter-receiver powered by a batteryhoused within a case of the radio wave transmitter-receiver; and arepeating apparatus mounted on said vehicle side for communicating withsaid radio wave transmitter-receiver, said radio communication apparatusmounted on one of said helmets communicating with a second of saidhelmets through said repeating apparatus, wherein said radio wavetransmitter-receiver includes a pair of operation buttons disposed oneabove another on one side of a rear face of the case; and a coil antennaaccommodated along an upper inner side of the case, said radio wavetransmitter-receiver being mounted in a predetermined posture at thecenter of the rear portion of each of said helmets.